Hi @Sandeepa,
Sorry to hear you're having issues unlocking your device 
Can you clarify a couple of things for me? When you say you can't unlock your device, is there a screen pattern or PIN that you have set up and is not being accepted when you try to unlock your phone or is the screen not responding to touch and that's why you can't unlock it?
Or is this a differen't type of lock you have, network lock for example?
Please let me know 
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